new: option to prepend banner on top of the output

Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>

main.go

@@ -4,13 +4,16 @@ import (
 	"bufio"
 	"fmt"
 	"os"
+	"time"
 
 	"github.com/leodido/maintainers-generator/pkg/version"
 
 	"github.com/sirupsen/logrus"
 	"k8s.io/test-infra/prow/config/secret"
 )
 
+var defaultBanner = "# Do not edit this file manually.\n# Made using github.com/leodido/mantainers-generator"
+
 func main() {
 	o := NewOptions()
 	// Early exit in case user wants to only know the version
@@ -71,12 +74,33 @@ func main() {
 	}
 
 	w := bufio.NewWriter(output)
-	n, err := w.WriteString(out)
+
+	n1 := 0
+	if o.banner {
+		dt := time.Now()
+		n1, err = w.WriteString(
+			fmt.Sprintf(
+				"%s on %d-%02d-%02dT%02d:%02d:%02d\n",
+				defaultBanner,
+				dt.Year(),
+				dt.Month(),
+				dt.Day(),
+				dt.Hour(),
+				dt.Minute(),
+				dt.Second(),
+			),
+		)
+		if err != nil {
+			logrus.WithError(err).WithField("output", o.outputFile).Fatal("Unable to write output file.")
+		}
+	}
+
+	n2, err := w.WriteString(out)
 	if err != nil {
 		logrus.WithError(err).WithField("output", o.outputFile).Fatal("Unable to write output file.")
 	}
 	w.Flush()
 	if o.outputFile != "stdout" {
-		logrus.WithField("no. of bytes", n).Info("Wrote output file.")
+		logrus.WithField("no. of bytes", n1+n2).Info("Wrote output file.")
 	}
 }

options.go

@@ -15,7 +15,6 @@ import (
 type Options struct {
 	dryRun         bool
 	github         prowflagutil.GitHubOptions
-	hmacSecret     string
 	version        bool
 	logLevel       string
 	org            string
@@ -25,6 +24,7 @@ type Options struct {
 	personsFile    string
 	outputFile     string
 	personsSupport bool
+	banner         bool
 }
 
 // Validate validates the receiving options.
@@ -68,8 +68,7 @@ func (o *Options) Validate() error {
 func NewOptions() *Options {
 	o := Options{}
 	fs := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-	fs.BoolVar(&o.dryRun, "dry-run", true, "Dry run for testing (uses API tokens but does not mutate).")
-	fs.StringVar(&o.hmacSecret, "hmac", "/etc/webhook/hmac", "Path to the file containing the GitHub HMAC secret.")
+	fs.BoolVar(&o.dryRun, "dry-run", false, "Dry run for testing (uses API tokens but does not mutate).")
 	fs.BoolVar(&o.version, "version", false, "Print the version.")
 	fs.BoolVar(&o.dedupe, "dedupe", true, "Whether to dedupe or not sub-project areas for every maintainer.")
 	fs.BoolVar(&o.sort, "sort", true, "Whether to sort the projects alphabetically.")
@@ -80,6 +79,7 @@ func NewOptions() *Options {
 	fs.StringVar(&o.repo, "repo", "", "The GitHub repository name.")
 	fs.StringVar(&o.personsFile, "persons-db", "data/data.json", "The path to a JSON file containing handle => name/company mappings")
 	fs.StringVar(&o.outputFile, "output", "stdout", "The path where to write the output YAML maintainers")
+	fs.BoolVar(&o.banner, "banner", false, "Whether you want a header on top of the output YAML maintainers file")
 
 	for _, group := range []flagutil.OptionGroup{&o.github} {
 		group.AddFlags(fs)